Method and radio signature position determining entity (RS-PDE) for maintaining location database reliability

BACKGROUND OF THE INVENTION

00011. Field of the Invention

0002The present invention relates to Radio Signature Position Determining Entities (RS-PDEs) for mobile phones.

00032. Description of the Related Art

0004Cellular telecommunications networks are well known systems that provide radio service to an ever-growing number of Mobile Stations (MSs) subscribers via a network of Base Stations (BSs), themselves connected to one or more switching nodes. Various types of cellular telecommunications networks exist, including but being not limited to the Time Division Multiple Access (TDMA) based ANSI-41 cellular networks, the Global System for Mobile communications (GSM) networks, the Code Division Multiple Access (CDMA) based networks, and the Third Generation (3G) cellular telecommunications networks (e.g. W-CDMA, CDMA2000, GSM-based EDGE).

0005In recent years, various countries around the world, including the United States, have introduced legislations governing mobile station location requirements for the wireless subscribers community. According to these requirements, in an emergency situation involving a mobile subscriber, the mobile station would have to be located by the cellular telecommunications network within a given distance, so that law enforcement agencies can use the location information to intervene more efficiently for solving the emergency situation.

0006Conversely, locating mobile subscribers is also useful for operators of the cellular telecommunications networks, which can use the mobile subscriber location information for providing location-based services to the mobile community, such as for example regional news, location-based information for various proximally located events, or even location-based advertisement for local businesses. There is therefore also an imperative commercial need for locating a mobile station as precisely as possible.

0007Various methods exist for locating a mobile station in a cellular telecommunications network. The most straightforward method involves including a GPS transceiver into the mobile stations, wherein the GPS transceiver registers the actual position of the mobile station in terms of latitude and longitude. In this implementation, the location information can be provided to the cellular network upon request, or on a regular basis, for both emergency situations and commercial purposes. However, the drawback of the GPS-based method for locating a mobile station is that only a limited portion of the active mobile stations currently comprises a GPS transceiver. Therefore, the GPS-based method does not fulfill the current needs of the cellular industry for locating every active mobile station of a network.

0008Another way for locating a mobile station is the so-called triangulation method that involves first measuring radio timing parameters of the signals from the mobile station at special listening receivers, typically collocated with three or more base stations, that simultaneously communicate with a central positioning processor. The processor derives the time differences for the received signal as measured at each receiver and then computes the position of the mobile station using a geometric triangulation. Many variants of the triangulation method exist, including some that use the received signal strength instead of the time of arrival parameter for the geometric triangulation. Although certain triangulation methods are relatively precise, the provisioning of large numbers of listening receivers and the requisite communication channels to the central processor translates into significant initial investments for the mobile network operators desiring to implement the triangulation method for locating their cellular subscribers.

0009Yet another method for locating mobile stations of a cellular telecommunications network is a Radio Signature Positioning System that involves the use of a Radio Signature Positioning Determining Entity (RS-PDE). A typical RS-PDE comprises a processor for computing the position of mobile stations using a positioning algorithm and an associated Radio Signature location database (RS-DB) that contains radio signature data records for all points on a grid that overlays the area of interest. An RS-PDE is used to locate a mobile station by comparing a series of signal strength measurements taken by the mobile station to be located with signal strength measurements stored in the RS-PDE, in order to determine the best match. The best matching record found in the location database of the RS-PDE is assumed to also comprise the current location of the mobile station. <figref idref="DRAWINGS">FIG. 1</figref> (Prior Art) is an exemplary high-level illustration of such an RS-PDE <b>100</b> that comprises a virtual grid <b>101</b> that overlaps a physical cellular network <b>108</b>, the grid <b>101</b> having a series of squares <b>103</b> which positions are represented by their respective center points. The grid point RS-PDE further comprises a grid point location database <b>102</b> where each position of a geographic point like the points <b>105</b> of the grid <b>101</b> is represented with a measured (and/or predicted, in some implementations) radio signal strength of radio communications that a mobile station receives from its current cell and from its neighboring cells, when the MS is located at a given position represented by that grid point. Typically, the grid point database is populated with radio data measured in the cellular network by a testing mobile station that roams in the area of interest and measures the received signal strength in every point of interest. For example, in the exemplary scenario of <figref idref="DRAWINGS">FIG. 1</figref>, three cells <b>112</b>, <b>114</b>, and <b>116</b> of the cellular network are represented with their corresponding base stations <b>118</b>, <b>120</b>, and <b>122</b>, although it is understood that a typical cellular network may include a more significant number of cells. The base stations transmit control signals on their respective downlink Digital Control Channels (DCC) <b>124</b>, <b>126</b>, and <b>128</b>. At the grid point location <b>104</b>, a testing mobile station equipment <b>130</b> receives the radio signals on the DCCs <b>124</b>, <b>126</b> and <b>128</b> and measures their signal strength levels at that precise location, which geographical coordinates are also recorded via, for example, GPS means. The data collected by the testing mobile station equipment <b>130</b> in the point <b>104</b>, as well as from the other points of the grid, is used to populate the location database records like the exemplary database record <b>150</b>. Thus, by multiplying the number of measurements performed by the testing equipment <b>130</b> at different grid point locations, the location database <b>102</b> is populated with multiple records <b>1</b>–<i>m </i>showing the measured signal strength levels at each one of these multiple locations of the grid <b>101</b>.

0010The exemplary location record <b>150</b> is shown in <figref idref="DRAWINGS">FIG. 1</figref> as comprising a Mobile Switching Center Identity (MSC ID) <b>152</b> that provides the identity of the MSC servicing the service area where there radio signal strength measurements were registered, and a serving cell identity <b>154</b> providing the identity of the serving cell <b>112</b> used for the radio signal strength measurements. The location record <b>150</b> further comprises the actual position <b>156</b>, in terms of latitude and longitude, that may have been measured using GPS means included in the testing mobile station equipment <b>130</b>, and a series of n radio signal strength measurements <b>158</b> performed on the DCCs of the serving and neighboring cells of the cellular telecommunications network. For example, the parameter DCC_—CH<b>1</b>_—SS <b>158</b>₁may represent the received signal strength measured on the digital control channel of the serving cell <b>112</b>, while the parameter DCC_—CH<b>2</b>_—SS <b>158</b>₂represents the signal strength measured on the digital control channel of a first cell <b>114</b> of n cells adjacent or geographically close to the serving cell <b>112</b>. In order to have reliable measurements, the number n is typically selected between 6 and 12, thus allowing radio signal strength measurements to be done first on the serving cell, and further to 5–11 adjacent or closely located cells.

0011Once the location database <b>102</b> is populated with signal strength data for each grid point of the grid <b>101</b>, a Mobile Positioning Center (MPC) <b>162</b> with access to the RS-PDE's processor <b>160</b> and to the location database <b>102</b> may find the location of any mobile station of the cellular network for responding to emergency situations as described hereinbefore, or simply for a commercial sake. The MPC <b>162</b> sends a series of D_—CCs signal strength measurements taken by the mobile station to be located to the RS-PDE, where an RS-PDE Processor <b>162</b> compares these measurements with the records of the location database <b>102</b>, for determining the best match. The best matching record found in the location database <b>102</b> is assumed to represent the current location of the mobile station, which is provided in terms of position information including the longitude and latitude parameters from the positioning field <b>206</b> of the best matching record <b>150</b>.

0012The RSPDE is a reliable means for providing mobile station location information at reasonable costs for the network operator. However, the level of the radio signal strength data that is initially measured during the field test of the testing mobile station equipment <b>130</b> and that populates the database <b>102</b> forms the basis for the location algorithm. It was detected that over long periods of times the measured signal strength in a given location may vary due to i) the continue adjustments of the cellular network's topology (e.g. the cell definitions may be changed by the network operator to adapt to the changing traffic load), and to ii) seasonal and environmental changes (e.g. during the fall, trees of a forest lose their leaves thus changing the level of the measured signal strength in the area, an imposing building is constructed at the given location, etc). Since radio propagation conditions change with respect to the initial time where the testing equipment <b>130</b> collected the initial radio data, the mentioned factors introduce an error in the calculation of the position based on the signal strength, which negatively influence the performance of the grid point RS-PDE.

0013Although there is no prior art solution as the one proposed hereinafter for solving the above-mentioned deficiencies, the co-owned patent application entitled “Determination of Mobile Station Location”, Ser. No. 10/095,958, filed in U.S. Patent and Trademark Office on Mar. 13, 2002 in the name of Gennady Bayder, hereinafter called Bayder bears some relation with the field present invention. Bayder teaches a system, method and processing unit for mobile station location determination. In Bayder, Mobile Assisted Handoff (MAHO) measurements are sent to a processing unit that also retrieves the corresponding transmitted signal strengths and electromagnetic field distribution functions for the relevant base stations. The location of the mobile station is then determined by minimising the following formula: <maths id="MATH-US-00001" num="00001"><math overflow="scroll"><mrow><mrow><mi>F</mi><mo>⁡</mo><mrow><mo>(</mo><mrow><mi>γ</mi><mo>,</mo><mi>x</mi><mo>,</mo><mi>y</mi></mrow><mo>)</mo></mrow></mrow><mo>=</mo><mrow><munderover><mo>∑</mo><mrow><mi>j</mi><mo>=</mo><mn>1</mn></mrow><mi>m</mi></munderover><mo>⁢</mo><mrow><mi>M</mi><mo>⁡</mo><mrow><mo>(</mo><mrow><msub><mi>P</mi><mrow><mi>R</mi><mo>⁢</mo><mstyle><mspace width="0.3em" height="0.3ex" /></mstyle><mo>⁢</mo><mi>j</mi></mrow></msub><mo>-</mo><mrow><mi>γ</mi><mo>·</mo><msub><mi>P</mi><mrow><mi>T</mi><mo>⁢</mo><mstyle><mspace width="0.3em" height="0.3ex" /></mstyle><mo>⁢</mo><mi>j</mi></mrow></msub><mo>·</mo><mrow><msub><mi>G</mi><mi>j</mi></msub><mo>⁡</mo><mrow><mo>(</mo><mrow><mi>x</mi><mo>,</mo><mi>y</mi></mrow><mo>)</mo></mrow></mrow></mrow></mrow><mo>)</mo></mrow></mrow></mrow></mrow></math></maths><br /> where m is the number of relevant base stations, M is an optimisation metric (such as (ε_j)²or |ε_j|) P_Rjis received signal strength, P_Tjtransmitted signal strength, γ attenuation (e.g. in the mobile station), and G_j(x,y) the electromagnetic field distribution function. Bayder's teaching is limited to a method and corresponding system for calculating a location of a mobile station using a specific algorithm defined by the above-mentioned formula, and therefore Bayder fails to teach or suggest any method or system for ensuring the consistency and the reliability of a grid point RS-PDE.

0014The co-owned patent application entitled “System and Method of Estimating the Position of a Mobile Terminal in a Radio Telecommunications Network”, filed in U.S. Patent and Trademark Office on Jan. 10, 2002, in the names of Havish Koorapaty, Wang Wade, Zhu Guwei, and Panakanti Viswanath, hereinafter called Koorapaty, also bears some relation with the field of the present invention. Koorapaty teaches a system and method of estimating the position of a mobile terminal operating in a radio telecommunications network. Expected received signal strength values are predicted by a computer prediction tool, and/or are measured by a test mobile terminal from base station transceivers. The predicted and measured received signal strength values are then tagged to indicate whether each value was predicted or measured. The received signal strength values are then stored at a plurality of locations in a database. When the received signal strength measurements are received from the mobile terminal being located, a covariance matrix is used to compute metrics for the locations in the database. If more than a threshold percentage of the locations were populated with measured values, a maximum likelihood estimator is used to estimate the position of the mobile terminal. Otherwise, if fewer then a threshold percentage of locations were populated with measured values, a minimum mean square error estimator is used to estimate the position. Koorapaty is limited to teaching a system and method for estimating the position of the mobile terminal, and therefore fails to teach or suggest anything with relation to the reliability of the location data in a grid point RS-PDE.

0015Accordingly, it should be readily appreciated that in order to overcome the deficiencies and shortcomings of the existing RS-PDE implementations, it would be advantageous to have a simple yet efficient method and system for insuring the continuous reliability of the signal strength data that is used by a grid point RS-PDE system. The present invention provides such a method and system.

SUMMARY OF THE INVENTION

0016According to the present invention, a method and a Radio Signature Position Determining Entity (RS-PDE) are provided for maintaining the reliability of a location database of the RS-PDE. A Data Transfer Scheduler (DTS) of the RS-PDE receives new location data comprising signal strength measurements records, and the new location data is correlated by a Data Correlation Device (DCD) with existing location data of the location database. The correlated location data is uploaded by a Data Uploader (DU) into the location database. A Data Performance Monitor (DPM) detects if the RS-PDE provides better positioning results using that correlated data, and if so, the RS-PDE then uses the correlated data for mobile station positioning. The location data update cycle may be triggered by a configurable timer defining an update periodicity, or by a detection of insufficient positioning accuracy of the RS-PDE using the existing location data.

0017In one aspect, the present invention is a method for updating a location database of an RS-PDE, the method comprising the steps of transferring new location data to the RS-PDE, correlating the new location data with existing location data of the location database and creating correlated location data, and uploading the correlated location data into the location database.

0018In another aspect, the present invention is an RS-PDE including a location database comprising existing location data used for mobile station positioning; a Data Transfer Scheduler (DTS) receiving new location data; a Data Correlation Device (DCD) correlating the new location data with the existing location data of the location database and creating correlated location data; and a Data Uploader (DU) uploading the correlated data into the location database.

BRIEF DESCRIPTION OF THE DRAWINGS

0019For a more detailed understanding of the invention, for further objects and advantages thereof, reference can now be made to the following description, taken in conjunction with the accompanying drawings, in which:

0020<figref idref="DRAWINGS">FIG. 1</figref> (Prior Art) is an exemplary high-level illustration of a Radio Signature (RS) Positioning System that makes use of a Radio Signature Position Determining Entity (RS-PDE) for locating mobile stations of a cellular system;

0021<figref idref="DRAWINGS">FIG. 2</figref> is an exemplary high-level block diagram of an RS-PDE according the preferred embodiment of the present invention;

0022<figref idref="DRAWINGS">FIG. 3</figref> is an exemplary flowchart diagram illustrative of the functioning of a Data Transfer Scheduler (DTS) of the RS-PDE according to the preferred embodiment of the present invention;

0023<figref idref="DRAWINGS">FIG. 4</figref> is another exemplary flowchart diagram illustrative of the functioning of the RS-PDE according to the preferred embodiment of the present invention;

0024<figref idref="DRAWINGS">FIG. 5</figref> is an exemplary flowchart diagram illustrative of the functioning of a Data Correlation Device (DCD) of the RS-PDE according to the preferred embodiment of the present invention; and

0025<figref idref="DRAWINGS">FIG. 6</figref> is an exemplary flowchart diagram illustrative of the functioning of a Data Performance Monitor (DPM) of the RS-PDE according to the preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

0026The innovative teachings of the present invention will be described with particular reference to numerous exemplary embodiments. However, it should be understood that this class of embodiments provides only a few examples of the many advantageous uses of the innovative teachings of the invention. In general, statements made in the specification of the present application do not necessarily limit any of the various claimed aspects of the present invention. Moreover, some statements may apply to some inventive features but not to others. In the drawings, like or similar elements are designated with identical reference numerals throughout the several views, and the various elements depicted are not necessarily drawn to scale.

0027According to the preferred embodiment of the present invention, there is provided a method and system for updating the location information of a location database of a Radio Signature Position Determining Entity (RS-PDE) once it is detected a triggering event. The triggering event may be, for example, when it is detected that the existing location information of the location database is no longer reliable enough, such as for example when the positioning performed using the location information of the RS-PDE is no longer sufficiently precise, or at the expiration of a timer defining a periodicity for the location database update. The invention provides several functional modules that are provided in an RS-PDE, modules which constitute an automated data integrity mechanism for the PDE. The invention allows for the download of new radio measurements data, also called herein radio signature location data, or simply location data, from an associated data collection system, and for the automated scheduling of all the involved processes required to maintain the radio signature location database performance of the RS-PDE. The invention further provides for the monitoring of the accuracy performance of the RS-PDE, for the analysis of the performance and for the initiation, when required, of a transfer of new measurements data into the RS-PDE location database in order to improve its accuracy. The invention further provides for a correlation of the new location data with the existing location data from the location database, in order to optimize the accuracy performance, as well as for means for validating the integrity of the updated location data.

0028Referring now to <figref idref="DRAWINGS">FIG. 2</figref>, depicted therein is an exemplary high-level block diagram of an RS-PDE <b>200</b> implementing the preferred embodiment of the present invention. The RS-PDE <b>200</b> comprises an internal RS location database <b>202</b> for storing RS location data to be used for locating mobile phones, the location data being in the form of signal strength measurements records, such as for example alike the record <b>150</b> shown and described with relation to <figref idref="DRAWINGS">FIG. 1</figref>. The RS-PDE further comprises a processor <b>203</b> responsible for running an algorithm for processing location requests from the external Mobile Positioning Center (MPC, not shown) using the location information from the location database <b>202</b>. The RS-PDE <b>200</b> has access to a Signal Strength (SS) measurements server <b>204</b> that receives signal strength measurements <b>206</b> collected by a mobile station testing equipment <b>130</b> during field tests in areas of interest of a cellular system (not shown). The signal strength measurements <b>206</b> may be stored by the S.S. server <b>204</b> in a location server database <b>208</b> in the form of location records like the location record <b>150</b> described hereinbefore.

0029According to the preferred embodiment of the present invention, the RS-PDE <b>200</b> is provided with an RS location database automatic update module <b>205</b> responsible for implementing the invention into the RS-PDE <b>200</b>. The RS location database automatic update module <b>205</b> comprises a Data Transfer Scheduler (DTS) <b>210</b> which functions to control the transfer of new location data in the form of new radio measurements from the associated data collection server <b>204</b> into the RS-PDE <b>200</b>, action <b>209</b>. The DTS <b>210</b> may comprise a timer <b>212</b> responsible for triggering an update of the location database <b>202</b> at regular time intervals. The update of the location database <b>202</b> may be alternatively triggered by a decrease of the reliability of the location information stored in the RS location database <b>202</b>, as detected by a Data Performance Monitor (DPM) <b>214</b> of the RS location database automatic update module <b>205</b>, which function is yet to be described. The DTS <b>210</b> is also connected to administrative Graphical User Interface (GUI) <b>216</b> of the RS-PDE <b>200</b> that allows network administrators to configure the various components of the RS-PDE <b>200</b>.

0030Reference is now made concurrently to <figref idref="DRAWINGS">FIG. 2</figref>, previously introduced, and to <figref idref="DRAWINGS">FIG. 3</figref>, which shows an exemplary flowchart diagram illustrative of the functioning of the DTS <b>210</b> when transferring new location data from the S.S. server <b>204</b> according to the preferred embodiment of the present invention. In action <b>206</b>, new location data is collected and stored on the S.S. server <b>204</b> in the form of location data records like the record <b>150</b> of <figref idref="DRAWINGS">FIG. 1</figref>. The DTS <b>210</b> requests in action <b>207</b> new location data from the SS server <b>204</b> for a given Mobile Switching Center (MSC) service area. The purpose of requesting the new location data from the S.S. server <b>204</b> is to use that data for making a comparison with existing location data records of the location database <b>202</b> for determining the accuracy of a location computed based on the existing location records of the location database <b>202</b>. The DTS <b>210</b> receives in action <b>209</b> preferably all the relevant location data available from the S.S. Server <b>204</b>. In action <b>211</b>, the DTS <b>210</b> may optionally discard the received location data that has timestamps older than a predefined number of days, so that only recent location data is used. Finally, in action <b>213</b>, the DTS <b>210</b> sorts the newly received location data by position, and may temporarily store the sorted location data in a DTS database <b>217</b>, action <b>215</b>.

0031Reference is now made jointly to <figref idref="DRAWINGS">FIG. 2</figref> and to <figref idref="DRAWINGS">FIG. 4</figref>, which is another exemplary flowchart diagram illustrative of the functioning of the RS-PDE <b>200</b> according to the preferred embodiment of the present invention. Once the DTS <b>210</b> has the new location data sample received in action <b>209</b>, action <b>215</b>, it may perform an optional sampling of the data <b>209</b> by, for example, randomly selecting one or more records from the location data sample, action <b>400</b>. In action <b>402</b>, the DTS <b>210</b> may replace the channel identity of each one of the selected records with their associated cell identity, in the case wherein the records received in the sample <b>209</b> have the field <b>154</b> (shown in <figref idref="DRAWINGS">FIG. 1</figref>) provisioned with the channel number information instead of the cell identity information. For example, in action <b>402</b>, the DTS <b>210</b> may map a channel number 796 used by a given network operator to a serving cell identity XX0076, based on a mapping table (not shown) comprising an association between the channel numbers used by that network operator and the cell identities associated to these channel numbers. In action <b>404</b>, the new location data sample <b>405</b> chosen in action <b>400</b> is sent from the DTS <b>210</b> to the DPM <b>214</b>, which may first sort by cell ID the records of the sample <b>405</b>, action <b>406</b>. Then, the DPM <b>214</b> calculates, for each cell with location data records in the data sample <b>405</b>, the performance of the current location database <b>202</b>. For this purpose in action <b>408</b>, the DPM <b>214</b> selects one cell of all the cells with location data records in the data sample <b>405</b>, and in action <b>410</b> the DPM <b>214</b> computes a Figure of Merit (FoM) illustrative of the exactitude of the calculated positioning for the existing sampled records related to that cell. The determination of action <b>410</b> may comprise, first, the selection of a record from the sample, action <b>412</b>, then the transmission, action <b>414</b>, of a positioning request made to the RS-PDE database <b>202</b> on the basis of the radio measurements <b>158</b> (shown in <figref idref="DRAWINGS">FIG. 1</figref>) of the selected record, the return of the deducted position by the location database <b>202</b>, the calculation of a difference between the deducted position and the actual geographical position considered to be the GPS-measured position provided by the field <b>156</b> of the sampled record, action <b>416</b>, and the storage of the results, action <b>418</b>. In action <b>420</b>, it is detected if all records of the sample <b>405</b> have been processed and if not, the actions <b>412</b>–<b>418</b> are repeated for every one of these records. Finally, in action <b>422</b>, a figure of merit is computed for the cell being analyzed. Action <b>422</b> may comprise, for example, the calculation of an average of the differences calculated for each one of the records as shown in action <b>416</b>, or the 67^thbetter or worst percentile of the list of the differences calculated for the records in the same action <b>416</b>.

0032The calculated FoM is representative of and/or proportional to the error on the positioning requests made to the active location database <b>202</b> in the area covered by the cell being analyzed. Once that figure of merit for that cell is calculated via the sequence of actions <b>410</b>, in action <b>424</b> it is detected whether or not that figure of merit is above a pre-defined threshold and if not, the under consideration is not tagged for an automatic update of the location data, action <b>426</b>. Otherwise, if figure of merit is above the threshold, in action <b>428</b>, the DPM <b>214</b> tags that cell for an automatic update of its location data. In action <b>429</b>, the DPM <b>214</b> detects if all cells for which location data records have been provided in the sample <b>405</b> are processed and if not, the actions <b>408</b>–<b>428</b> are repeated for every remaining cell. The DPM <b>214</b> further detects whether or not at least one cell is tagged for an automatic location data update, action <b>430</b>, and if not, sends a no update required message to the DTS <b>210</b>, action <b>432</b>. Otherwise, if at least one cell is tagged for an automatic update of the location data, the DPM <b>214</b> sends an update-required message to the DTS <b>210</b>, action <b>434</b>. The DTS <b>210</b> may further detect in action <b>436</b> if the location data update feature is activated and if not, may issue an alarm notification informing the network administrator that a manual update of the location data is required, action <b>438</b>. If the automatic update feature is activated, in action <b>440</b> the DTS <b>210</b> may request from the server <b>204</b> all the location data available for the cells that have been tagged for the automatic update, by issuing the request <b>442</b> and receiving, responsive to that request, the relevant data <b>444</b> comprising signal strength measurements records for the cells of interest. Again, in action <b>442</b>, the DTS <b>210</b> may replace the channel number information with the cell identity information, if this is required and has not been previously done by the S.S. server <b>204</b>. Then, the DTS <b>210</b> sends the location data <b>449</b> received in action <b>444</b> for the cells of interest to a Data Correlation Device (DCD) <b>446</b> of the RS location database automatic update module <b>205</b>, action <b>448</b>, which performs a correlation between the existing location data of the location database <b>202</b> and the new location data sent in action <b>448</b>.

0033Reference is now made to <figref idref="DRAWINGS">FIG. 5</figref>, which is an exemplary flowchart diagram illustrative of the functioning of the DCD <b>446</b> of the RS-PDE <b>200</b> according to the preferred embodiment of the present invention. <figref idref="DRAWINGS">FIG. 5</figref> shows an exemplary correlation process <b>450</b> performed by the DCD <b>446</b> between the new location data and the existing location data of the database <b>202</b>. The purpose of this correlation process is to take into consideration both the existing location data and new location data before updating the location database <b>202</b>. This may be useful in various situations and implementation, such as for example when only a limited amount of new location data is available, or when a network operator prefers to gradually update the existing location data.

0034With reference to <figref idref="DRAWINGS">FIG. 5</figref>, when the location data update is triggered, such as detected in action <b>430</b> of <figref idref="DRAWINGS">FIG. 4</figref> when at least one cell is tagged for an automatic location data update, the DCD <b>446</b> begins to correlate the old and the new location data for the tagged cells. When performing the correlation, the received location data <b>444</b> may be first sorted by location and timestamp and then correlated to the equivalent location data of the existing database records. The correlation may include associating those new records of the location data <b>444</b> with the current database <b>202</b> records, and ensuring that the record lengths are compatible. With reference being now concurrently made to <figref idref="DRAWINGS">FIG. 2</figref> and <figref idref="DRAWINGS">FIG. 5</figref>, in action <b>500</b> the DCD <b>446</b> receives location data <b>449</b> for the cells tagged for the location data automatic update. In action <b>502</b>, the DCD <b>446</b> sorts the records of the location data by cell identity (CellId), and by position. In action <b>503</b>, the DCD <b>446</b> may insure that sufficient new location data records are available for each cell having location data records in the sorted list. If a cell is detected with insufficient records, it is considered that the new location data for that cell cannot positively influence the positioning related to that cell, and in action <b>505</b>, that cell is discarded from consideration, its related data being discarded, and the method goes to treating the next cell. If sufficient data is available for the other cells from the sorted list, the DCD <b>446</b> further retrieves the existing location data records that correspond to the remaining tagged cells from the current RS-PDE location database <b>202</b>, action <b>504</b>, and in action <b>506</b>, aligns the newly received location data records <b>449</b> with the location data records <b>505</b> from the location database <b>202</b>. The alignment of the action <b>506</b> may be performed based on the position information comprised in each one of these records, so that the aligned records from the newly received location data and the existing location data of the database <b>202</b> have similar position information. In action <b>508</b>, the DCD <b>446</b> selects a location data record from the location database <b>202</b> that represents a grid point of the grid <b>101</b> (shown in <figref idref="DRAWINGS">FIG. 1</figref>) as well as all the new location data records which position is within a given range of that grid point's location, such as for example ±25 m from the grid point. In action <b>510</b>, the DCD <b>446</b> checks the timestamp and may optionally discard the newly received location data records that are older than a predefined number of days, so that only new location data is considered for the location data correlation. In action <b>512</b>, the DCD <b>446</b> performs an average of the signal strength values of the remaining new location data records having position information within the given range, and further, in action <b>514</b> computes an average, or alternatively a weighted average, of the signal strength values of the selected existing record of the location database on one side, and the signal strength average value computed in action <b>512</b> on the other side. Finally, in action <b>516</b>, the DCD <b>446</b> creates an updated location data record including the latest timestamp of the new location data, the signal strength values averaged in action <b>514</b>, and the current position of the grid point under consideration. In action <b>518</b>, the DCD <b>446</b> detects if all the grid points of interest for the tagged cells have been considered, and if not, repeats the actions <b>508</b>–<b>516</b> for each one of the remaining grid point. Otherwise, in action <b>520</b>, the DCD <b>446</b> formats the correlated location data into a location data file to be uploaded in the RS-PDE location database, and sends that file to an RS-PDE Data Uploader (DU) <b>524</b>, action <b>522</b>.

0035Reference is now made back concomitantly to <figref idref="DRAWINGS">FIG. 2</figref> and <figref idref="DRAWINGS">FIG. 4</figref>, wherein in action <b>460</b> the DU <b>524</b> performs an upload of the correlated location data into an upload RS location database <b>203</b>. Further, in action <b>462</b>, the DPM <b>214</b> is instructed to perform a verification of the correlated location data in order to ensure that location data uploaded into the upload RS location database <b>203</b> provides better positioning accuracy results than the old location data stored in the location database <b>202</b>.

0036Reference is now made concurrently to <figref idref="DRAWINGS">FIG. 2</figref> and <figref idref="DRAWINGS">FIG. 6</figref> that shows an exemplary flowchart diagram representative of the verification process performed by the DPM <b>214</b> according to the preferred embodiment of the present invention. The shown verification process validates that the newly correlated location data allows the RS-PDE <b>200</b> to have improved positioning accuracy following the location data correlation. Once the correlated location data upload is performed, action <b>460</b>, the DTS <b>210</b> transmits a request for verification message, action <b>602</b>, to the DPM <b>214</b>, the message also comprising the cells that were tagged for the automatic update. In action <b>606</b>, the DPM <b>214</b> selects one cell of the tagged cells, and in action <b>608</b> invokes a positioning request subroutine similar to the one performed in action <b>410</b> shown in <figref idref="DRAWINGS">FIG. 4</figref>, wherein the positioning request subroutine computes a Figure of merit (FoM) for that cell using location data records from the uploaded location database <b>203</b>. In action <b>610</b>, the DPM <b>214</b> obtains the FoM for that same cell that was previously computed in action <b>422</b> of <figref idref="DRAWINGS">FIG. 4</figref>, which FoM is representative of the location accuracy provided by the RS-PDE using existing location data records from the active location database <b>202</b>. In action <b>612</b>, the two FoMs are compared. If the FoM computed using the correlated location data records form the database <b>203</b> is above the FoM computed using the old location data records from the database <b>202</b>, then the cell under consideration is tagged as improved, action <b>614</b>, since the FoM is representative of the positioning accuracy provided by the RS-PDE using a given set of data. Otherwise, in action <b>614</b>, the cell under consideration is marked as not improved. In action <b>616</b>, the DPM <b>214</b> further determines if all the tagged cells were processed, and if not, repeats steps <b>606</b>–<b>614</b> for each remaining cell. If all the tagged cells were processed, then in action <b>618</b> the DPM <b>214</b> further determines if more than a certain threshold percentage of the tagged cells have improved, and if so, sends an automatic update accept message to the DTS <b>210</b>, the message being indicative of the acceptance of the location data correlation update. Otherwise, if fewer than the threshold number of cells have improved, it is considered that the correlated data is not more reliable than the existing location data of the database <b>202</b>, and the DPM <b>214</b> sends an update reject message to the DTS <b>210</b>, action <b>622</b>.

0037Reference is now made back to <figref idref="DRAWINGS">FIG. 4</figref>, wherein following action <b>618</b>, the DTS <b>210</b> instructs the activation of the upload location database <b>203</b> if an improvement is detected, action <b>470</b>. Action <b>470</b> may comprise a replacement of the location database <b>202</b> by the upload location database <b>203</b>, which becomes the active location database of the RS-PDE <b>200</b>, thus completing the location data update according to the preferred embodiment of the present invention. Alternatively, the DTS <b>210</b> instructs the keeping of the currently active location database <b>202</b>, action <b>472</b>, if an improvement is not detected in action <b>618</b>.

0038In a variant of the preferred embodiment of the invention, the timer <b>212</b> controls and trigger the location data update cycle. According to this variant, at regular time intervals defined by the timer T <b>212</b>, itself controlled and configured by the administrative GUI <b>216</b>, triggers the process of updating the location data of the location database <b>202</b>. Thus, with reference being made to <figref idref="DRAWINGS">FIG. 4</figref>, actions <b>440</b>–<b>472</b> may be performed responsive to a timeout of the timer <b>202</b>, thus allowing for a periodic RS location database update with new RS location data.

0039In yet another variant of the preferred embodiment of the invention, the verification process <b>462</b> illustrated in <figref idref="DRAWINGS">FIG. 6</figref> may be skipped, so that once the location data update cycle is triggered by the timer <b>202</b> timeout or as described in relation to steps <b>400</b>–<b>436</b> of <figref idref="DRAWINGS">FIG. 4</figref>, the location database update takes place automatically without any further verification of the positioning accuracy of the newly correlated data.

0040In yet another variant preferred embodiment of the invention, the cells referred to in the foregoing description may not only represent a radio cell of the cellular telecommunication network under consideration, but any other area larger or smaller than a radio cell. Thus, the present invention allows a network operator to select a variable granularity of the areas under consideration for the RS location data update according to the present invention. For example, the cell referred to in the foregoing description may relate to a radio cell area, to a group of one or more radio cells, to a sub-cell area, or to any other sub-division of the cellular telecommunications network.

0041In yet another variant of the preferred embodiment of the invention, the RS location database automatic update module <b>205</b> shown in <figref idref="DRAWINGS">FIG. 2</figref> as being included in the RS-PDE <b>200</b>, may be external and only connected to the RS-PDE <b>200</b>, although from a logical point of view, the functionalities provided according to the present invention can be viewed as being comprised in the RS-PDE.

0042Based upon the foregoing, it should now be apparent to those of ordinary skill in the art that the present invention provides an advantageous solution, which facilitates the maintenance of the RS-PDE location database reliability. Further, the invention provides for a method, system and RS-PDE that implements means for automatically detecting an event for performing a location data update, and means for carrying out the location data update when such event is detected (timer timeout or availability of new location data) means. Although the system and method of the present invention have been described in particular reference to certain exemplary actions for carrying out the invented concept, it should be realized upon reference hereto that the innovative teachings contained herein are not necessarily limited thereto, and may be implemented advantageously using different steps. It is believed that the operation and construction of the present invention will be apparent from the foregoing description. While the method and system shown and described have been characterized as being preferred, it will be readily apparent that various changes and modifications could be made therein without departing from the scope of the invention as defined by the claims set forth hereinbelow.

0043Although several preferred embodiments of the method and system of the present invention have been illustrated in the accompanying Drawings and described in the foregoing Detailed Description, it will be understood that the invention is not limited to the embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the spirit of the invention as set forth and defined by the following claims.